Secondary wound dressings for securing primary dressings and managing fluid from wounds, and methods of using same

ABSTRACT

Under one aspect, an apparatus includes a primary dressing configured for application over a region of compromised skin and including fluid-absorbing material; and a secondary dressing configured for application over the primary dressing. The secondary dressing applies pressure to the primary dressing so as to maintain the primary dressing in place over the region of compromised skin and promote the flow of fluid from the region of compromised skin into the fluid-absorbing material, and allows moisture in the fluid to evaporate from the fluid-absorbing material. Under another aspect, a dressing includes a fabric layer sized to cover a region of compromised skin; a foam layer secured to the fabric layer and having an aperture defined therein sized to cover the region of compromised skin; and a biocompatible adhesive layer disposed on the foam layer. Methods of applying the dressing also are provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part under 35 U.S.C. §120 of U.S.patent application Ser. No. 12/788,077, filed May 26, 2010 now abandonedand entitled “Deformable and Conformable Wound Protecting Apparatus andits Method of Application,” which is a continuation of U.S. patentapplication Ser. No. 11/107,452, filed Apr. 16, 2005 now U.S. Pat. No.7,745,683 and entitled “Deformable and Conformable Wound ProtectingApparatus and its Method of Application,” the entire contents of both ofwhich are incorporated by reference herein.

This application is also a continuation-in-part under 35 U.S.C. §120 ofU.S. patent application Ser. No. 12/416,826, filed Apr. 1, 2009 now U.S.Pat. No. 8,067,662 and entitled “Systems and Methods for WoundProtection and Exudate Management,” the entire contents of which areincorporated by reference herein.

FIELD OF THE INVENTION

This application relates to secondary wound dressings for securingprimary dressings, and methods of using same.

BACKGROUND OF THE INVENTION

Wounds occur when the integrity of any tissue is compromised, affectingone or more layers of skin. Wounds may be caused by an act, surgicalprocedure, an infectious disease or an underlying condition. Acutewounds may be caused by an initiating event, such as a accident-relatedinjury, surgical procedure or by operation of an infectious disease, andgenerally take the form of punctures, abrasions, cuts, lacerations, orburns. Chronic wounds are wounds that generally do not heal in orderlystages or in a predictable amount of time, the way many other wounds do;for example, chronic wounds typically do not heal within three months.Chronic wounds may, for example, be due to one or more of: ischemia ofthe vessels supplying the tissue, venous hypertension or compromise ofthe immune response, such as observed, for example, with venous ulcers,diabetic ulcers and pressure ulcers. Depending on etiology, such asdiabetes, venous insufficiency, or cardiovascular failures, acute woundsmay become recalcitrant and even chronic.

Injurious contacts with foreign objects may be caused from varioussources, ranging from brushing of clothing or bed sheets to fresh,uncovered wounds to adherence of wound dressing to the wound. The latterissue, referred to here as the sticking issue, leads to deleteriousconsequences for the patient. This problem is particularly exacerbatedwhen wounds are left unattended for a substantial period. It is reportedthat in certain circumstances patients are administered morphine towithstand the pain caused form dressing removal, especially with woundshaving a large surface area. Equally important, tearing of skin graft,newly formed cells or scab adhered to dressing disrupts the healingprocess.

The introduction of bacteria from external sources into the woundtypically causes inflammation that activates the patient's immuneresponse, in turn causing white blood cells, including neutrophilgranulocytes, to migrate towards the source of inflammation. While theyfight pathogens, such neutrophils also release inflammatory cytokinesand enzymes that damage cells. In particular, the neutrophils produce anenzyme called myeloperoxidase that in turn is metabolized to producereactive oxygen species that kill bacteria. Collaterally, such enzymesand reactive oxygen species damage cells in the margin surrounding thewound, referred to as the “periwound region,” thereby inhibiting cellproliferation and wound closure by damaging DNA, lipids, proteins, theextracellular matrix and cytokines that facilitate healing. Becauseneutrophils remain in chronic wounds for longer than in acute wounds,they contribute to higher levels of inflammation. Moreover, thepersisting inflammatory phase in chronic wounds contributes to exudate(fluid that flows from the wound) with high concentrations of matrixmetalloproteases (MMPs). Excess MMPs results in degradation ofextracellular matrix protein. In addition to damaging the wound, exudatedamages the periwound tissue exposed to it as well. In particular,exudate that flows out of the wound and onto periwound region may damagethe fragile skin, which is already compromised due to the patientsunderlying etiology, such as diabetes. Such damage may degrade theperiwound skin and cause its breakdown and turn it into a wound. Thus,exudate flow onto the periwound region may cause many complications,including the potential for increasing the size of the wound andprolonging its healing. Such damage to the skin in the periwound region(periwound skin) may make the skin more susceptible to tearing andresultant intense pain as dressings or devices adhered to them areremoved. Other complications may include, for example, infection of theperiwound region and intense itching.

Patients suffering from chronic wounds frequently report experiencingsevere and persistent pain associated with such wounds, which may arisefrom necrosis of and/or nerve damage of the skin and underlying tissue.Treatment for such pain often consists of low dose analgesics, whiletopical antibiotics and/or debridement, which seeks to remove necrotictissue from the wound, may be used to control the bacterial load at thewound site.

Conventional wound treatment also typically involves covering the woundwith a primary dressing to prevent further contamination and infection,to retain moisture, and to absorb exudate. By “primary dressing” it ismeant a dressing used to cover the wound, without any interveningdressing between the wound and the primary dressing. While exudatecontains biochemical compounds that benefit wound healing as notedabove, its excessive amount in wound or its presence in the periwoundregion facilitates degradation of tissue, and the exudate additionallyserves as a growth medium for bacteria. The consistency of exudatevaries, depending on the type of wound and the stage of healing. Forexample, exudate may be watery, extremely viscous, or somewhere inbetween. Moreover, the sizes of wounds can vary greatly, as can theircare.

Although a wide variety of primary dressings have been developed, fewpreviously-known wound treatment systems properly manage exudate, e.g.,by removing a sufficient amount of exudate from the wound site, whileprotecting the periwound region from damaging contact with the exudate.Moreover, conventional systems typically do not address the pain createdby the wound treatment system, particularly where the wound treatmentsystem continuously contacts the wound. For example, gauze, which isapplied directly onto a wound, is capable of absorbing only a limitedamount of exudate, and readily transports excess exudate onto theperiwound region, causing maceration and damage. Moreover, the gauzetypically is in direct contact with the wound and adheres to it, so thatnormal motion of the patient results in rubbing, itching and discomfort.In addition, removal of the gauze at periodic intervals is painful andfrequently disrupts any healing that may have occurred.

Some previously-known approaches to wound treatment attempt to reduceadhesion between the wound and the primary dressing by applyingadditional substances. For example, the wound and dressing may be soakedin saline water to loosen adherence and/or soften any scabs that formed,thus facilitating removal of the dressing. Or, for example, antibioticointments such as polymyxin B sulfate or bacitracin can be applied toreduce sticking. However, such methods are not always satisfactorybecause soaking a particular wound in water or applying ointments maynot be practicable or recommended.

Some previously-known primary dressings are promoted as being“non-stick” or “non-adherent,” such as TELFA™ and XEROFORM™, and otherbrands that may be composed of materials such as hydrocolloids,alginates, and hydrofilms. Regardless of the level of adherence of suchdressings to the wound, continuous contact between the primary dressingand wound disturbs the fragile wound matrix, and may undermine thegrowth of blood vessels and epithelial cells in the wound bed. Suchdisturbance often occurs when the dressing is removed, or simply as aresult of the contact between the bandaged area and the patient'senvironment. Pain is often concomitant with such disturbances. Inaddition, previously-known “non-stick” dressings usually do not absorbsufficient amounts of exudate, and thus require frequent monitoring andchanging. These drawbacks add to the cost of use and limit theapplicability of such previously-known wound treatment systems.

Previously-known primary dressings commonly have only a limited abilityto manage wound exudate. As noted above, prolonged exposure of otherwisehealthy skin to exudate may cause degradation of the periwound region.The moisture of the exudate may cause maceration, which is a softeningof the skin that compromises its integrity and makes the skin in theperiwound region vulnerable to physical insult and infection.

Some previously-known primary dressings attempt to manage exudate toaddress the foregoing issues, but provide either limited benefit and/orat a much higher perceived cost. For example, a foam dressing such asALLEVYN® (marketed by Smith & Nephew, Largo, Fla., USA) is designed toabsorb large amounts of exudate. However, use of this product isrestricted to highly exuding wounds, because its highly absorptiveproperties can result in desiccation of wounds that are not highlyexuding, thereby impeding healing. In addition, because foam used inthat product cannot be conformed to the size and shape of the wound, thedressing typically overlaps with the periwound region. Consequently,exudate absorbed by the foam is transported throughout the foam and ontothe periwound region, where prolonged exposure leads to maceration anddegradation of the periwound region. Other previously-known dressings,such as ACQUACEL® hydrofiber dressing (available from ConvaTec, Inc.,Princeton, N.J., USA) contact the wound bed, and are intended to absorbexudate and transfer and sequester the exudate in a layer disposed atopthe wound. This and similar previously-known dressings do not entirelycontain or absorb exudate. Moreover, like foam and otherpreviously-known dressings, hydrofiber dressings essentially plug thewound surface, and create an osmotic environment in which the fluidicosmotic pressure within the wound bed approximates that of thesurrounding tissue. Consequently, exudate is not sufficiently drawn fromthe wound, and its buildup in the wound may adversely affect the woundand periwound region. Furthermore, ALLEVYN®, ACQUACEL®, and similarpreviously-known primary dressings do not provide an adequate moisturevapor transfer rate (MVTR) away from the wound environment, thuscreating the potential for an over-hydrated environment that hinderswound healing.

Other previously-known wound treatment systems, such as the V.A.C.®system, available from Kinetic Concepts, Inc. (San Antonio, Tex., USA),employ a mechanically operated contact-based dressing that continuouslyvacuums exudate from the wound bed. It and other dressings incorporatingthe concept of Negative Pressure Wound Therapy have proven particularlyuseful in healing large wounds, such as surgical wounds. However, suchsystems are costly, difficult to apply and time consuming. In addition,because such systems require insertion of a sponge (for the V.A.C.®system) or gauze (as commercialized by other wound care companies)directly into the wound bed, they likely cause considerable pain anddiscomfort for the patient, and may not be appropriate for many types ofwounds.

Several previously-known primary dressings also have been developed thatare promoted as “non-contact” dressings, which seek to prevent adhesionof the wound tissue to dressing, or to facilitate certain treatmentsthat by their nature cannot contact the wound, e.g., thermal therapy.Such dressings are commonly formed as an inverted cup or a raisedbandage that covers the wound without contacting it. Suchpreviously-known primary dressings, however, also have failed toadequately heal wounds and protect the periwound region. Suchnon-contact dressings are provided in pre-formed shapes and sizes, andhave limited deformability, thus limiting their ability to preventexposure of the periwound skin to exudate. Additionally, the limiteddeformability of such previously-known dressings makes application ofsuch dressings difficult or impossible to wounds on small surfaces or inareas with complex topology, such as the ankle or foot. Previously-knownnon-contact primary dressings also do not allow the pressure applied tothe periwound region to be readily managed, and may result in theformation of pressure rings around the wound, thereby inducing ischemiain the wound and surrounding tissue. Finally, such previously-knownprimary dressings do not provide any mechanism to stimulate the flow ofexudate, nor do they sequester exudate away from the wound in anyappreciable volume. Such previously-known primary dressings also traphumidity over the wound and periwound region, leading to maceration,periwound degradation and impeded healing.

In some circumstances, secondary dressings are used to secure primarydressings over a wound. However, it may not always be practicable orsafe to secure a primary dressing using a previously-known secondarydressing, such as an ACE™ elastic bandage (3M). For example, using sucha bandage to secure a primary dressing over an upper body wound mayinvolve wrapping the bandage around the entire torso, which mayundesirably compress internal organs, may be uncomfortable, and also maybe inconvenient to place and remove on a frequent basis. Other bodyparts over which it may be difficult to secure primary dressings includejoints that undergo a relatively large range of motion during normaluse.

SUMMARY OF THE INVENTION

The present invention provides secondary wound dressings for securingprimary dressings and managing fluid from wounds, and methods of usingsame. The secondary dressings include a fabric layer that is larger thanthe primary dressing, and a biocompatible adhesive layer disposed alongthe periphery of the fabric layer. The biocompatible adhesive layer maybe secured to the skin about the primary dressing, which brings thefabric layer into contact with the primary dressing. The heightdifference between the primary dressing and the skin imposes a tensionon the fabric, which causes the fabric to apply pressure to the primarydressing. The magnitude of the pressure can be selected appropriatelybased on the type of wound and the type of primary dressing. Such afeature is particularly useful when the primary dressing is to besecured onto a part of the body where previously-known types ofsecondary dressings cannot be placed conveniently or safely, such as onthe upper body, or on a joint. The secondary dressings also are highlybreathable, allowing fluid from the wound that may be absorbed by theprimary dressing to evaporate into the air.

In some embodiments, the secondary dressings of the present inventionmay be used in conjunction with primary dressings that manage exudateand cushion wounds from external pressure sources. The primary andsecondary dressings may be used individually, or in conjunction with oneanother, for a wide range of chronic and/or acute wounds, includingvenous ulcers, pressure ulcers, and surgical wounds. In addition,dressings constructed in accordance with the present invention may beadvantageously used for surgical wounds to protect the incision site,particularly for surgical areas where skin is most vulnerable, such assplit-thickness graft sites and cosmetic surgeries, as well as forregions of the skin that are compromised but not necessarily wounded.

Primary and/or secondary dressings constructed in accordance with thepresent invention also may advantageously be used to treat acute woundsand to protect the wound from further trauma, such as occurs inindustrial accidents and in the battle field settings. In particular,dressings in accordance with the present invention may be applied toreduce contact pressure on the wound bed. In a battlefield setting, forexample, this aspect of the invention may be particularly valuable,since a bandaged wound may still have debris or shrapnel in it, and theprimary and/or secondary dressings can be applied to prevent suchcontaminants from being pushed further into the wound during evacuationof the wounded subject.

According to one aspect of the present invention, an apparatus forprotecting a region of compromised skin includes a primary dressingconfigured for application over the region of compromised skin, theprimary dressing including fluid-absorbing material; and a secondarydressing configured for application over the primary dressing. Thesecondary dressing is configured to apply pressure to the primarydressing so as to maintain the primary dressing in place over the regionof compromised skin and so as to promote the flow of fluid from theregion of compromised skin into the fluid-absorbing material, and isfurther configured to allow moisture in the fluid to evaporate from thefluid-absorbing material.

In some embodiments, the secondary dressing includes a fabric layer anda biocompatible adhesive layer, the adhesive layer disposed along aperiphery of the fabric layer and configured to secure the fabric layerover the primary dressing. The secondary dressing may further include afoam layer disposed between the fabric layer and the biocompatibleadhesive layer, the foam layer having an aperture therein, the aperturebeing larger than the primary dressing. The fabric layer may include awoven fabric or a nonwoven fabric. In some embodiments, the fabric layerhas a machine direction and a cross direction, and wherein an elasticityof the fabric layer is different in the machine direction than anelasticity of the fabric layer in the cross direction. The pressureapplied by the secondary dressing on the primary dressing may be basedon an orientation of the machine and cross directions of the fabriclayer.

In some embodiments, the primary dressing includes a strip of theexudate-absorbing material, the strip having first and second ends, alower surface, an upper surface, and a length, the upper and lowersurfaces being parallel to one another along the length. The strip maybe adapted to flex along its length to circumscribe the region ofcompromised skin. The primary dressing may further include an adhesivedisposed on the lower surface of the strip, the adhesive securing thestrip adjacent the region of compromised skin.

In some embodiments, the primary dressing further includes a supportcushion configured to surround the region of compromised skin and theexudate-absorbing material. The primary dressing may further include abiocompatible adhesive configured to secure the support cushion aroundregion of compromised skin and the exudate-absorbing material.

The primary dressing may further include a reservoir configured to besuspended over and in engagement with the exudate-absorbing material sothat the material transfers exudate from the region of compromised skinto the reservoir. The primary dressing may further include a coverconfigured to be positioned over the reservoir, the secondary dressingbeing in contact with the cover.

The secondary dressing may have a moisture vapor transfer rate (MVTR)that is greater than an MVTR of the primary dressing.

Under another aspect of the present invention, a dressing for protectinga region of compromised skin includes a fabric layer sized to cover theregion of compromised skin; a foam layer secured to the fabric layer andhaving an aperture defined therein, the aperture being sized to coverthe region of compromised skin; and a biocompatible adhesive layerdisposed on the foam layer.

In some embodiments, the foam layer extends to a periphery of the fabriclayer. The foam layer may be hydrophobic. The foam layer optionallyincludes slits for breathability. The foam layer optionally includesperforations enabling adjustability of the dressing's size and/or thetension that the foam layer applies to the fabric layer.

The fabric layer may include a woven fabric or a nonwoven fabric. Thefabric layer may have a machine direction and a cross direction, and anelasticity of the fabric layer may be different in the machine directionthan an elasticity of the fabric layer in the cross direction.

Under another aspect of the present invention, a method for protecting aregion of compromised skin includes applying a primary dressing over aregion of compromised skin, the primary dressing includingfluid-absorbing material; applying a secondary dressing over the primarydressing, the secondary dressing configured to apply pressure to theprimary dressing so as to maintain the primary dressing in place overthe region of compromised skin and so as to promote the flow of fluidfrom the region of compromised skin into the fluid-absorbing material,the secondary dressing further configured to allow moisture in the fluidto evaporate from the fluid-absorbing material.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B and are an exploded view and a cross-sectional view,respectively, of an exemplary primary dressing, while FIG. 1C is apartial sectional view illustrating transfer of exudate from the woundto the reservoir via the wicking strip of the primary dressing of FIGS.1A and 1B.

FIG. 2 illustrates steps in accordance with one method of managingexudate with a primary dressing.

FIG. 3 illustrates a perspective view of an illustrative application ofa primary dressing of FIGS. 1A-1C to a patient.

FIG. 4 schematically illustrates a plan view of one preferred embodimentof a support cushion and wicking strip suitable for use in a primarydressing.

FIGS. 5A-5C illustrate alternative embodiments of a wicking stripsuitable for use in a primary dressing.

FIGS. 6A-6B illustrate further alternative embodiments of a wickingstrip suitable for use in a primary dressing.

FIG. 7 schematically illustrates a plan view of a reservoir, cover, andoptional vent according to some embodiments of a primary dressing.

FIG. 8 is a plan view of an alternative embodiment of a support cushionand wicking strip suitable for use in a primary dressing.

FIG. 9 is a plan view of another alternative embodiment of a supportcushion and wicking strip suitable for use in a primary dressing.

FIG. 10 is a perspective view of an embodiment of a primary dressingthat includes a lavage system, in which the wicking strip has beenomitted for improved clarity.

FIG. 11 is a perspective view of an embodiment of a primary dressingthat includes a manually-operated bellows for applying a negativepressure within the dressing.

FIGS. 12A and 12B respectively are an exploded view, and a partialsectional view, of another embodiment of a primary dressing.

FIGS. 13A and 13B respectively are a plan view, and a perspective view,of an alternative embodiment of a cover and reservoir suitable for usein a primary dressing.

FIG. 14 schematically illustrates a plan view of a kit containing aprimary dressing.

FIGS. 15A-15B respectively illustrate plan and cross-sectional views ofa secondary dressing, according to some embodiments of the presentinvention.

FIG. 15C illustrates the use of the secondary dressing of FIGS. 15A-15Bwith the primary dressing of FIGS. 1A-1C, according to some embodimentsof the present invention.

FIG. 16 illustrates steps in accordance with one method of securing aprimary dressing and managing fluid from a wound with a secondarydressing.

FIG. 17 is a plan view of an alternative secondary dressing, accordingto some embodiments of the present invention.

FIG. 18 is a cross-sectional view of another alternative secondarydressing, according to some embodiments of the present invention.

FIG. 19 is a cross-sectional view of another alternative secondarydressing, according to some embodiments of the present invention.

FIGS. 20A-20B respectively illustrate plan and cross-sectional views ofyet another alternative secondary dressing, according to someembodiments of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides secondary wound dressings for protectingand promoting wound healing by securing primary dressings over a wound,and managing fluids that may be released by the wound. In someembodiments, the secondary wound dressings include a fabric layer, afoam surround, and a biocompatible adhesive layer. The fabric layerincludes a lightweight material that, in some embodiments, has amoisture vapor transmission rate (MVTR) that is at least as great as theMVTR of the primary dressing over which it is applied. As such, thefabric layer allows for the ready evaporation of any fluids from thewound that may have been captured by the primary dressing, as describedin greater detail below. The foam surround includes upper and lowersurfaces and a central aperture that is at least as large as the primarydressing. The upper surface of the foam surround is suitably secured tothe fabric layer, and the biocompatible adhesive layer is disposed onthe lower surface of the foam surround. During use, the central apertureof the foam surround is approximately centered over the primarydressing, which has already been placed over the wound. The foamsurround is then secured around the primary dressing by pressing thebiocompatible adhesive layer against the patient's epidermis around theprimary dressing, which brings the fabric layer into contact with theprimary dressing. When the secondary dressing is secured to thepatient's epidermis via the biocompatible adhesive layer, the heightdifference between the primary dressing and the foam surround appliestension to the fabric, which in turn applies a gentle compressive forceto the primary dressing. The magnitude of this compressive force may beadjusted by preselecting the elasticity of the fabric layer, asdescribed in greater detail below. As such, the secondary dressingallows primary dressings readily to be secured with a desired pressureover any desired body part, including the upper body, wherepreviously-known secondary dressings typically cannot be used safely orconveniently.

In some embodiments, the primary wound dressing is selected to allow thewound to remain moist, while at the same time may transfer excess fluid,such as exudate, away from the wound and periwound region to aseparately located reservoir that is elevated above the wound. In thismanner, neither the wound nor the periwound region come into prolongedcontact with excess fluid, such as exudate, and thus both may beprotected from maceration or bacterial action that degrades tissue andskin. The secondary dressing may facilitate the evaporation of fluidfrom the reservoir, further reducing the risk of maceration. Such anarrangement may further promote wound healing by reducing the disruptionof the wound bed (and pain) caused by periodic replacement ofpreviously-known primary dressings, such as gauze, which adhere to thewound bed. Both the primary and secondary dressings also may allow theflow of exudate from the wound to be managed by manipulating the amountand profile of pressure applied to the periwound skin, which also isexpected to enhance the rate of healing of the wound.

First, exemplary embodiments of primary dressings that may be used withthe secondary dressings will be described, as well as a method ofapplying and using the primary dressings. Further details on theindividual components employed in the primary dressings, and alternativeembodiments and methods, will then be described. Then, exemplaryembodiments of secondary dressings will be described, as well as amethod of applying and using the secondary dressings with a variety ofprimary dressings, including the primary dressings described herein.Alternative embodiments of secondary dressings will then be described.

Overview of Illustrative Primary Dressing

FIGS. 1A and 1B illustrate an exemplary embodiment of a primary wounddressing 10 that may be used in conjunction with the secondary wounddressings described in greater detail below. In this exemplaryembodiment, primary dressing 10 comprises three discrete components thatare assembled and applied by the patient, nurse, clinician or othercaregiver over wound W on patient's epidermis E. In particular, primarydressing 10 includes support cushion 20, wicking strip 30, and reservoir40, preferably pre-attached to cover 50. Preferably, components 20, 30,40 and 50 of dressing 10 are sized for use with one another and areenclosed in a sterile package with suitable instructions to enable thepatient or caregiver to quickly and accurately apply the dressing.Alternatively, because for some embodiments certain components ofprimary dressing 10, such as wicking strip 30 and/or reservoir 40, maybe replaced on a frequent basis than other portions of the primary, suchcomponents may be individually packaged.

Support cushion 20 preferably comprises a closed-cell polyolefin foamand is designed to surround wound W and periwound region P, i.e., theregion of epidermis E extending from the wound margin, to protect thewound and elevate reservoir 40 and cover 50 above the wound bed. In theillustrated embodiment, support cushion 20 has a stepped profile,including sidewall 21 and flange 22. The upper surface of flange 22forms ledge 23 that supports reservoir 40, as depicted in FIG. 1B. Lowersurface 24 of support cushion 20 includes layer 25 of biocompatibleadhesive, which preferably is hydrophobic and breathable, and inhibitsexudate from leaking onto periwound region P. Upper surface 26 ofsupport cushion includes layer 27 of adhesive or a portion of a reusablefastening system, e.g., the pile of a hook and pile fastening system,such as Velcro. Use of a non-permanent adhesive for layer 27 permits thecover to be removed to periodically replace wicking strip 30 and/orreservoir 40, as described below. In addition, support cushion 20preferably includes slits or perforations 28 that extend through theheights of sidewall 21 and flange 22 to facilitate moisture vaportransfer, e.g., the escape of perspiration from beneath support cushion20, when the cushion is fastened by adhesive layer 25 to epidermis E.Support cushion 20 includes opening 29 that exposes a portion of theperiwound region P extending away from the margin of wound W, to permitplacement of wicking strip 30, as depicted in FIG. 1B.

Wicking strip 30, which preferably comprises an open-cell polyurethanefoam, overlays periwound region P between the margin of wound W andflange 22 of support cushion 20. In the embodiment of FIGS. 1A-1B,wicking strip 30 is depicted as a curved strip of foam, although ittakes other forms as described herein for alternative embodiments.Wicking strip 30 preferably includes layer 31 of biocompatible adhesive,which preferably is hydrophobic and breathable, and inhibits contactbetween exudate and the periwound region P, on lower surface 32. Duringapplication, wicking strip 30 may be rolled to a tighter spiral thandepicted in FIG. 1A, such that it fits snugly within opening 29 ofsupport cushion 20 and the innermost edge of the wicking strip overlapsthe margin of the wound by 1-2 mm. Note, however, that wicking strip 30need not necessarily overlap the margin of the wound. For example, theinner edge of wicking strip 30 may be substantially even with the marginof the wound, or the inner edge of wicking strip may be spaced apartfrom the margin of the wound, e.g., 1-2 mm away from the margin of thewound, leaving a small region of the periwound skin uncovered by thewicking strip. For the embodiment of FIG. 1A, wicking strip 30 may becut with a scissor to ensure that the foam is not overly compressed whenadhered to the periwound region by layer 31. In a preferred embodiment,establishing snug contact between the outermost edge of wicking strip 30and the inner-facing surface of flange 22 ensures that exudate does notleak onto an exposed portion of the periwound region between wickingstrip 30 and support cushion 20. Alternatively, outer-facing surface 32of wicking strip 30 may employ a hydrophobic film or coating thatprevents exudate from seeping into the periwound region.

Still referring to FIGS. 1A-1B, reservoir 40 preferably comprises asandwich of different density open cell polyurethane foams 41 and 42joined to mesh 43, in which the foams 41 and 42 are selected to absorbexudate from wicking strip 30 and to sequester the exudate away from thewound bed. In the embodiment depicted in FIGS. 1A-1B, reservoir 40 isfastened to the underside of cover 50, and is sized so that the outeredges of the reservoir are supported on ledge 23 of support cushion 20,while the more central regions of the reservoir engage the upper surfaceof wicking strip 30. Preferably, reservoir 40 fits within sidewall 21 ofsupport cushion 20, so that exudate drawn into the reservoir fromwicking strip 30 cannot seep out of the lateral face of the reservoir.As shown in FIG. 1B, flange 22 suspends reservoir 40 over wound W, thusinhibiting contact between reservoir 40 and wound W and limiting theextent to which force applied to cover 50 and reservoir 40 istransmitted to wicking strip 30. Wicking strip 30 may additionallysupport reservoir 40 over wound W. Optionally, a layer of adhesive maybe disposed on the lower surface of the reservoir 40 that engages ledge23 of the support cushion to removably secure those components together.Reservoir 40 preferably includes one or more vents 44 that assist inmodulating the humidity within the dressing through cover 50.

Cover 50, preferably a breathable material, overlays reservoir 40. Layer51 of adhesive preferably is used to removably secure reservoir 40 tocover 50. Alternatively, reservoir 40 may be removably fastened to cover50 using a removable fastening system, such as hook and pilearrangement. In addition, layer 27 of adhesive, or a removable fasteningsystem, is used to secure cover 50 to the upper surface of sidewall 21of support cushion 20, so that cover 50 and/or reservoir 40 may beperiodically removed from dressing 10 to inspect the wound, to applytopical medications or other substances to the wound, e.g., moisturizingointments, growth factors, nutrients, and/or antibiotics, or to replacewicking strip 30 or reservoir 40. In other embodiments, cover 50 and/orreservoir 40 are left in place over the wound while dressing 10 isapplied to the patient.

As described in greater detail below, the components of primary dressing10 may each be provided with one or more non-stick liners to facilitatehandling of the different components of the system, e.g., while placingsupport cushion 20 on epidermis E. The liners may be removed asappropriate to expose the adhesive layers and secure components toepidermis E or to each other.

Referring now to FIGS. 1B and 1C, during use of primary dressing 10,exudate EX flows out of wound W at a flow rate that depends on manyfactors, including the pressure with which wicking strip 30 is pressedagainst the periwound region, the lateral profile of wicking strip 30(described in greater detail below with reference to FIGS. 5A-5C), thecharacteristics of wound W, and the consistency of the exudate. Asexudate EX is released from the wound, some of the exudate pools on topof wound W. As discussed above, such accumulation of excess exudate withhigh concentrations of MMPs leads to degradation of extracellular matrixprotein both in the wound and on periwound skin. However, excess exudatemay flow from the wound, or gravity and/or patient movement may displaceexudate from the wound bed so that it contacts and is absorbed bywicking strip 30.

As depicted in FIG. 1C (from which cover 50 has been omitted forclarity), wicking strip 30 transports exudate EX laterally (in the planeof epidermis E) and then vertically (perpendicular to the plane ofepidermis E) to reservoir 40. Specifically, the exudate travels along agradient from relatively wet regions to relative dry regions of thewicking strip via capillary action. Exudate transported laterally mayeventually reach the inner surface of flange 22 of support cushion 20.Because support cushion 20 is formed of a hydrophobic material, itinhibits further lateral transport of the exudate. Instead, exudatepreferably is transported vertically from wicking strip 30 and intoreservoir 40, which sequesters exudate away from the wound. Inaccordance with one aspect of the invention, reservoir 40 preferably hasa large absorptive surface area and the capacity to hold large amountsof exudate, e.g., sufficient capacity so that reservoir 40 need only bereplaced once every few days (for example, every 7-10 days). Reservoir40 is also breathable, so that it releases water in the exudate in theform of vapor V into the atmosphere via breathable cover 50.Additionally, ledge 23, upon which reservoir 40 rests, and sidewall 21,adjacent to reservoir 40, are hydrophobic and cannot transfer exudatefrom reservoir 40 onto the periwound region. Further, adhesive layers 25and 31 are hydrophobic and further inhibit contact between exudate andthe periwound region P. Accordingly, multiple features of dressing 10are configured to inhibit prolonged contact between the exudate andperiwound region, and thus to inhibit maceration or other degradation ofthe periwound region, as observed with previously-known dressings.

Multiple features of primary dressing 10 both enhance the healing ofwound W and protect periwound region P from maceration and degradation.Among other things, although reservoir 40 is arranged to protect thewound from the environment and absorb exudate, it is suspended over andthus is not in continuous contact with the wound. This feature may bothreduce any pain experienced by the patient and promote healing. Forexample, initially placing reservoir 40 (and the other components ofprimary dressing 10) does not require touching the wound bed itself,resulting in significantly less pain than, for example, than the V.A.C.®or systems similar to it described above that rely on inserting a spongeor gauze directly into the wound. Wicking strip 30 and/or reservoir 40also may readily be removed without disrupting re-epithelialization ofthe wound. Moreover, because reservoir 40 sequesters the exudate, whenreservoir 40 is removed to observe the wound, exudate does not flow ontothe adhesive used to secure cover 50 to support cushion 20. Thisarrangement allows wicking strip 30 and/or reservoir 40 to be replacedand for cover 50 to be re-secured to support cushion 20, without havingto replace the entire dressing. By contrast, removing previously knowndressings (which contact the wound) often disrupts re-epithelializationand allow exudate to flow onto the adhesive, requiring the entiredressing to be discarded and a new one applied.

It is noted that although reservoir 40 is designed to be suspended over,rather than in contact with the wound, occasions may arise where thereservoir will contact the wound. For example, if sufficient pressure isapplied directly onto cover 50 and reservoir 40, the reservoir maydeflect sufficiently to contact the wound for as long as that pressureis applied. Such temporary contact is not believed to significantlyimpede the healing of the wound, and the durometer and resiliency ofsupport cushion 20 preferably is selected to provide adequate supportfor cover 50 and reservoir 40 in the expected range of applications.

Primary dressing 10 also encourages the flow of exudate from the wound,and thus reduces the bacterial load of the exudate in contact with thewound bed. Without wishing to be limited by theory, the inventorsbelieve that the flow of exudate from the wound may stimulate healing.First, primary dressing 10 encourages exudate flow by continuouslywicking exudate out of the wound, thereby providing a lower osmoticpressure at the wound than in the surrounding tissue. This osmoticpressure differential encourages exudate to flow from the surroundingtissue into the wound to attempt to equalize the osmotic pressure. Incontrast, conventional dressings that directly contact the woundtypically do not generate an osmotic pressure differential. In addition,because primary dressing 10 absorbs exudate from the wound and promotesreplenishment of exudate, the bacterial load of the exudate in contactwith the wound bed remains relatively low. Primary dressing 10 also isconfigured to allow a variety of different types of pressure to beapplied to the periwound region, depending on the type of wound, asdescribed in greater detail below with respect to FIGS. 5A-5C.

Additionally, primary dressing 10 is well-suited for use in treatingpressure sores that may be acquired by patients whose skin may bedamaged by, for example, continuously lying in bed without sufficientmovement. Such pressure sores may occur where skin is thin, has reducedintegrity, and/or where bone and skin are close together, withoutsufficient intervening muscle or fat. Support cushion 20 rests onregions of epidermis E that surround the wound, thus protecting thewound from the type of pressure that initially caused the wound. Supportcushion 20 may be formed of a supple, easily bendable material that doesnot create a pressure ring around the wound. In some embodiments,support cushion 20 is formed of a polyolefin that distributes pressure,inhibiting that pressure from concentrating in one region.

Overview of Method of Using Primary Dressing

FIG. 2 illustrates steps in a method 60 of using primary dressing 10 formanaging exudate from a wound, according to some embodiments of theinvention. Typically, the method is implemented by a physician, nurse,or other caregiver. However, the method is relatively simple to employ,and the patient himself may apply primary dressing 10.

First, at step 61, the caregiver obtains support cushion 20, wickingstrip 30, reservoir 40, and cover 50, e.g., a kit as described belowwith respect to FIG. 7. Next, in step 62, support cushion 20 is appliedto the epidermis of a patient, so that the support cushion surrounds thewound and periwound region. For example, a non-stick liner coveringlower surface 24 of support cushion 20 may be removed to expose theadhesive on its lower surface. The support cushion then is roughlycentered around the wound, and pressed onto the patient's epidermisusing gentle manual pressure. A non-stick liner covering layer 27 on theupper surface of support cushion 20 may be left in place until a laterstep, described below.

At step 63, wicking strip 30 is applied within the periwound regionbetween the margin of the wound and support cushion 20. For example,wicking strip 30 will include a non-stick liner covering layer 31, andthis liner will be removed to expose the adhesive. A first end ofwicking strip 30 then is applied and adhered to a first portion of theperiwound region, e.g., just overlapping the margin of the wound. Thefree end of the wicking strip then is spiraled around the wound, withsubsequent portions of wicking strip 30 adhered to adjacent portions ofthe periwound region, for example, as illustrated in FIG. 4, until theentirety of the periwound region exposed within opening 29 of thesupport cushion is filled. Preferably, wicking strip 30 fillssubstantially the entire periwound region between the wound and supportcushion 20, to prevent seepage of exudate from the outermost lateralface of the wicking strip. In some circumstances, the wound may besufficiently large that the entire wicking strip 30 is not needed tofill the periwound region between the wound and support cushion 20, inwhich case wicking strip 30 may be cut to the appropriate length. Thewound may have a relatively irregular shape, and simply spiralingwicking strip 30 around the wound will adequately fill the entireperiwound region. Alternatively, wicking strip 30 may be cut intomultiple pieces of appropriate lengths, which are individually adheredto the periwound region as appropriate.

At step 64, reservoir 40 and cover 50 (which is preferably pre-adheredto reservoir 40) then are applied over wicking strip 30. For example,the non-stick liner may be removed from layer 27 disposed on the uppersurface of side wall 21, and reservoir 40 inserted into support cushion20 so that the exposed adhesive on support cushion 20 adheres to cover50, as illustrated in FIG. 1B.

At step 65, compression wrap 70 optionally is wrapped over primarydressing 10 to apply a desired pressure onto the dressing and wound,e.g., as illustrated in FIG. 3. For example, as discussed above, theamount of applied pressure may affect the flow of exudate and the rateof healing of the wound, so the physician may elect to compress primarydressing 10. The appropriate amount of pressure and wrap type may differfrom wound to wound, and may be selected based on the physician'sknowledge and experience with particular wound types. Elasticcompression wraps such as PROFORE® (Smith & Nephew, Largo, Fla., USA)may suitably be used.

For example, if using an elastic compression wrap to compress primarydressing 10 against a venous leg ulcer, the wrap may be stretched beyonda specified proportion of its native length, and then secured in thatstretched configuration. The physician optionally may apply other wrapson dressing 10, such as gauze or Unna Boot or both. Such interveninglayers of material also may be applied with compression, as appropriate.

Some wound sites located on broad surfaces, such as the torso, may noteasily be wrapped with a compression wrap. In such circumstances, or inany other appropriate circumstance, a secondary dressing provided by thepresent invention may be used in place of the elastic compression wrapto secure and/or compress the primary dressing, as described in greaterdetail below. Alternatively, or additionally, the differential heightsbetween the support cushion, reservoir and wicking strip of primarydressing 10 may be adjusted to provide sufficient pressure to stimulatethe flow of exudate. For example, as described herein after with respectto the embodiment of FIGS. 5A to 5C, a wicking strip having a variableheight may be employed with the dressing of the present invention.Depending upon how the wicking strip is applied surrounding the wound,the dressing and compression wrap, if present, may be adjusted toprovider either greater or lesser pressure on the tissue surrounding thewound, or to provide a uniform pressure at the wound site in view ofcomplex limb topology.

Optionally, a medication or other substance may be applied to the woundor periwound region during any appropriate step in method 60. Forexample, the wound and periwound region may be cleaned, dried, and/ordebrided or moisturized before applying support cushion 20 to theepidermis. Or, for example, a wound dressing such as PROMOGRAN PRISMA™collagen and silver dressing (available from Systagenix WoundManagement, London, UK), or Dermagraft® (available from AdvancedBioHealing, La Jolla, Calif., USA), or Apligraf® (available fromOrganogenesis, Inc., Canton, Mass., USA), and other similar collagen orbiological dressings, may be applied to the wound after applying wickingstrip 30, but before applying reservoir 40 and cover 50. Othersubstances may be used, such as time-release topical medicines.

Further details of the construction of the individual components ofprimary dressing 10, and alternative embodiments, are now provided.

Support Cushion 20

Referring to FIG. 4, support cushion 20 and wicking strip 30 of primarydressing 10 are further described. Support cushion 20 includes sidewall21 and flange 22, which forms ledge 23. Each of sidewall 21 and flange22 includes plurality of slits 28 that enhances its breathability andflexibility. In particular, slits 28 may be arranged in radial orcircumferential directions, or with another preferred orientation toimprove conformability of the support cushion to the anatomy of aspecific limb. Support cushion 20 preferably is secured to patient'sepidermis using a biocompatible adhesive layer, which is preferablyhydrophobic but breathable, and additionally or alternatively may besecured using a compression wrap, gauze, ACE™ bandage, or Unna boot thatoverlays the dressing, or a secondary dressing of the present invention,such as illustrated in FIGS. 15A-20.

In some embodiments, support cushion 20 is of unitary construction, withsidewall 21 and flange 22 being formed from different portions of thesame piece of material. Alternatively, sidewall 21 and flange 22 may beindividually constructed and then heat-fused or adhesively bondedtogether, thus allowing the materials, thicknesses, and othercharacteristics of sidewall 21 and flange 22 to be selected and tailoredfor specific applications. For example, it may be preferable to formsidewall 21 using a relatively thick layer of a large-cell hydrophobicmaterial and flange 22 using a relatively thin layer of a small-cellhydrophobic material. Such a combination of materials and thicknessesimparts support cushion 20 with sufficient flexibility to be conformableto substantially any body part, e.g., an arm, leg, neck, or torso, whilemaintaining a sufficient level of hydrophobicity to prevent exudate fromleaking onto the periwound region. Examples of suitable hydrophobicmaterials for use in support cushion 20 include polyolefin, foams, andsilicone-based materials, in open cell or closed cell forms. Anysuitable adhesive or bonding procedure can be used to adhere sidewall 21to flange 22.

As mentioned above, slits 28 may enhance the flexibility andbreathability of support cushion 20, e.g., to allow support cushion 20to more readily conform to various body parts and to allow humidity inthe regions of the epidermis underlying support cushion 20 to escape,thus reducing maceration. Slits 28 may be simple “cuts” that extendthrough support cushion 20, e.g., through sidewall 21 and flange 22,without removing material. Alternatively, slits 28 may be aperturesformed by removing material from sidewall 21 and/or flange 22. Slits 28may be formed in any appropriate size, shape, density, or pattern. Forexample, slits 28 may extend in a single direction, as illustrated inFIG. 4, may extend radially (perpendicular to curvature of supportcushion 20), may extend parallel to the curvature of support cushion 20,or may extend at an angle relative to the curvature of support cushion20. Some slits 28 may extend at different angles than other slits 28.

Alternatively, support cushion 20 of the present invention may include aspacer fabric, such as the polyester/nylon spacer fabric designatedstyle DNB69, available from Apex Mills, Inward, N.Y., USA. Suchmaterials are hydrophobic, but include an open weave that is highlybreathable, thereby permitting moisture to readily evaporate from thepatient's skin during prolonged use, while preventing maceration.

In the embodiment illustrated in FIG. 4, support cushion 20 ispre-formed in a generally oval shape, and is suitable for use withwounds up to a fixed size, e.g., up to 30 mm in length. However, supportcushion 20 also may be formed in any other appropriate shape and sizeand may be provided having a range of size of openings 29 in flange 22.For example, support cushion 20 may be pre-formed in a generallycircular, rectangular, triangular, or other polyhedral shape, optionallyhaving rounded corners, or may even be pre-formed in an irregular shape.Alternatively, support cushion 20 may be formed as a strip that may beapplied around the wound and periwound region. The strip may be ofpredetermined length, or may even be provided on a roll and cut to adesired length. In such embodiments, it may be convenient to applysupport cushion 20 to the epidermis after wicking strip 30 is appliedaround the wound.

To accommodate such free-form embodiments of the support cushion, it maybe desirable for reservoir 40 and cover 50 to have a basket-likeconfiguration, such as described in detail below with respect to FIGS.13A-13B.

In still other embodiments (not illustrated), support cushion 20 may bean annular structure filled with a fluid, e.g., air or water, a gel, anexpanded plastic, or fibers. Such structure may be formed of moldedplastic, welded polymer, or a laminate.

Note that ledge 23 need not necessarily be included in all embodimentsof support cushion 20. For example, in embodiments omitting ledge 23,the lower surface of reservoir 40 directly contacts the upper surface ofwicking strip 30, which suspends reservoir 40 over wound W.

Wicking Strip 30

In the embodiment illustrated in FIG. 4, wicking strip 30 of primarydressing 10 is an elongated strip of hydrophilic material spiraledaround wound W in the space between the wound and the inner surface offlange 22. Preferably, wicking strip 30 is sufficiently flexible that itmay be applied in any desired pattern to the epidermis, e.g., that itmay be packed so as to fill substantially the entire space between thewound and the innermost surface of defining opening 29 of supportcushion 20. One example of a suitable hydrophilic, flexible material foruse in wicking strip 30 is an open-cell foam such as hydrophilicpolyurethane. Alternatively, wicking strip 30 may include any suitableabsorbent structure, e.g., a woven fabric, a nonwoven fabric, a hydrogel(which may include modified starch), or a pouch filled with a polymericabsorbent material. Layer 31 of biocompatible adhesive is disposed onthe lower surface of wicking strip 30, and may be hydrophobic so as toinhibit contact between exudate absorbed by wicking strip 30 and theperiwound region P.

In the embodiment of FIGS. 1A-1B, wicking strip 30 is depicted as havingthe same height as flange 22 of support cushion 20. However, wickingstrip 30 may actually have a different height than flange 22, butreservoir 40 may compress the two components to the same height duringuse. For example, wicking strip 30 may be thicker or thinner (taller orshorter, respectively) than flange 22, and may have a differentcompliance. In one embodiment, wicking strip 30 is thicker than flange22, but is more easily compressed, allowing both components to becompressed to the same thickness by reservoir 40 during use.

Likewise, wicking strip 30 may have a variable width along its length,as depicted in FIG. 1A. In other embodiments, such as that depicted inFIG. 4, the width of wicking strip 30 is essentially constant along itslength. Referring to FIG. 5A, an embodiment of a wicking strip isdepicted wherein a first end of wicking strip 30′ has a first height h₁,and a second end a second height h₂, wherein h₁ is less than h₂. Asillustrated in FIG. 5B, the asymmetrical-height wicking strip 30′ may beapplied to the periwound region with the first, shorter end adjacent tothe wound and the second, taller end furthest from the wound. Whenreservoir 40 is compressed onto wicking strip 30′ in this arrangement,wicking strip 30′ will apply a lower pressure adjacent to the wound, dueto the smaller amount of material being compressed, and a higherpressure further from the wound, due to the greater amount of materialbeing compressed in that region. While compressed, wicking strip 30′ mayappear to have the same height along its length, even though itsthickness varies in its native (non-compressed) state. Alternatively, asillustrated in FIG. 5C, wicking strip 30′ may be applied to theperiwound region with the second, taller end adjacent the wound and thefirst, shorter end furthest from the wound. When reservoir 40 iscompressed onto wicking strip 30′ in this arrangement, wicking strip 30′will apply a higher pressure adjacent the wound, due to the greateramount of material being compressed, and a lower pressure further fromthe wound, due to the smaller amount of material being compressed. Thearrangement of such an asymmetrical wicking strip 30′ may be selectedbased on the type of wound being treated. For example, pressure woundsmay benefit from a lower pressure being applied near the wound, whereasvenous leg ulcers may benefit from a higher pressure being applied nearthe wound. Other types of wounds may benefit from different pressuregradients being applied. In many embodiments, wicking strip 30 iscomposed of a supple material that, when pressure is applied to it, doesnot create a potentially harmful pressure ring around the wound.

As illustrated in FIGS. 4 and 5A-5C, the wicking strip may have arelatively even width along its length. However, the wicking strip ofthe present invention also may be provided in a variety of other shapesand sizes, depending on the intended application. FIG. 6A illustrates anembodiment in which wicking strip 30″ is additionally provided withrelaxation cuts 33 that enhance its lateral flexibility, therebyfacilitating lateral bending without buckling or crimping. Non-stickliner 34 is attached to layer 25 of adhesive, and may include tabs 35that facilitate application of the wicking strip.

FIG. 6B illustrates an embodiment in which wicking strip 30′″ ispre-formed in a bowed or arcuate shape, optionally including widerthicker portion 36, which may facilitate application of the wickingstrip around the wound by reducing the lateral bending required tosurround the wound. The degree to which wicking strip 30′″ is bowed mayvary, depending on the size of the wound with which it is intended to beused, and the compliance of the material. For example, wicking strip30′″ may be highly bowed, e.g., formed to be a spiral in its nativeconfiguration (before adhesion to the epidermis). FIG. 6B alsoillustrates tabs 35, which are part of or attached to non-stick liner 34and may facilitate removal of the liner, which may optionally beincluded in any embodiment of wicking strip 30.

In still other embodiments (not illustrated), the wicking strip ispre-formed into an annular form. If the inner boundary of such anannular form does not come sufficiently close to the border of the woundto protect the periwound region, then additional pieces of wicking stripmay be applied in the gap between the annular form and the margin of thewound.

Reservoir 40

As illustrated in FIGS. 1A-1B, reservoir 40 of primary dressing 10 mayinclude multiple layers bonded together or alternatively may be formedof a single, hydrophilic layer. In the embodiment of FIG. 1, reservoir40 includes upper layer 41, lower layer 42 and intervening layer 43.Lower layer 42 engages the upper surfaces of wicking strip 30, andtransfers exudate through intervening layer 43, and into upper layer 41.Although reservoir 40 is composed of breathable material that allows forthe transfer of moisture vapor as needed, reservoir 40 optionally maycontain vent 44 that extends through the reservoir to provide a lessimpeded route for moisture vapor transfer.

Referring again to FIG. 1B, both upper layer 41 and lower layer 42 arehydrophilic. However, layers 41 and 42 may have the same or differenthydrophilicities, mechanical properties, transfer rates for exudate, andcapacities for absorbing exudate. In some embodiments, layers 41 and 42are formed from hydrophilic polyurethane foams, e.g., commerciallypurchased polyurethane foams from Rynel, Inc. (Wicasset, Me., USA). Thefoam from which lower layer 42 is fabricated has a higher hydrophilicitythan that of upper layer 41, allowing it to rapidly transfer exudateinto upper layer 41. The polyurethane foams may be coated or interlacedwith any suitable antibacterial or antimicrobial agents (e.g., silver)to combat or prevent infection.

Intervening layer 43 enhances the strength and stiffness of reservoir40, making it more difficult to inadvertently deflect reservoir 40downward to contact the wound. Intervening layer 43 may be, for example,a substantially non-stretchable mesh or scrim, such as a metallic,nylon, or polyester-based mesh.

In some embodiments, layers 41, 42, and 43 are co-selected to enablereservoir 40 to form a dome-like shape as it absorbs exudate and swells,while still maintaining contact with ledge 23 and sidewall 21 of supportcushion 20. For example, intervening layer 43 may be formed to have alarger diameter than the diameter defined by the sidewall 21 of supportcushion 20. As reservoir 40 absorbs exudate and swells, this differencein diameter allows intervening layer 43 to buckle upward.

Cover 50

Referring now to FIGS. 1B and 7, cover 50 of primary dressing 10 isdescribed having pre-fastened reservoir 40 with vent 44. Cover 50 may beadhered to upper layer 41 with a layer of adhesive, or otherwiseattached to upper layer 41 before or after reservoir 40 is placed overthe wound. During use, cover 50 is adhered to sidewall 21 using layer 27of adhesive, which urges reservoir 40 against wicking strip 30. In someembodiments, cover 50 extends beyond the lateral dimensions of supportcushion 20, so that when primary dressing 10 is applied to a patient,cover 50 drapes over support cushion 20 and covers layer 27 of adhesive.Such draping protects the edges of support cushion 20 from lifting, andadditionally provides a smooth, comfortable surface over which clothingand bed linens may slide freely. In other embodiments, layer 27 maycomprise a removable fastener, such as a hook and pile arrangement thatenables the cover to be periodically removed to inspect the wound, applymedicaments, or to replace the wicking strip or reservoir.

Cover 50 is made of a soft, occlusive material that provides anantibacterial barrier between the wound and the environment, and alsoallows humidity to escape from reservoir 40 and vent 44. One example ofa suitable material for cover 50 is Intelicoat 2327, available fromIntelicoat Technologies (South Hadley, Mass., USA). The material may becoated or intercalated with any suitable antibacterial or antimicrobialagent to combat or prevent infection.

Additional Alternative Embodiments of Primary Dressing 10

Referring now to FIGS. 8 and 9, additional embodiments of supportcushions and wicking strips suitable for use in primary dressings aredescribed, which may simplify the construction and application of theprimary dressings. In FIG. 8, support cushion 70 comprises sidewall 71of uniform height defining opening 72 and wicking strip 80 disposedwithin opening 72. The upper surface of wicking strip 80 visible in FIG.8 is recessed below the top of sidewall 71 of support cushion 70 toaccept reservoir 40 and cover 50 as described with respect to precedingembodiments. Preferably, the height of wicking strip 80 is in a range of40-60% of the height of sidewall 71. In this embodiment, wicking strip80 is pre-adhered to support cushion 70 so that the lower surfaces ofsupport cushion 70 and wicking strip 80 are flush, and includes opening81 that may be used to visually position the unit over a wound. Wickingstrip 80 includes spiral perforation 82 that extends through the heightof the wicking strip, so that the perforation forms spiraled innerportion 83 of the wicking strip. The innermost end of the spiraledportion terminates at pull tab 84.

Support cushion 70 and wicking strip 80 preferably include a layer ofadhesive on the lower surface, similar to layer 25 in the embodiment ofFIG. 1B, which is covered by non-stick liner having removal tab 85.Support cushion 70 also includes layer 27 of adhesive or other suitablefastening means on its upper surface, and may include a plurality ofslits 28, as described for preceding embodiments, to improvebreathability and conformability of the support cushion. Reservoir 40and cover 50, as described for preceding embodiments, may be employed,so that the reservoir fits snugly within the recess above wicking strip80.

In the embodiment of the invention depicted in FIG. 8, spiraled portion83 of wicking strip 80 is configured to be removed, using pull tab 84,to unwind the wicking strip to just expose the margin of the wound. Thelength of the spiraled portion 83 that is unwound to expose the marginof the wound then is cut off with a scissor and discarded. In thismanner, the wicking strip may be easily positioned at the preferredlocation at the margin of the wound, with the remainder of wicking strip80 covering the periwound region, thereby reducing the time required toapply the inventive dressing. Once the support cushion and wicking stripare positioned, and the appropriate length of spiraled portion 83removed to expose the margin of the wound, the reservoir and cover thenis fastened atop support cushion 70 and wicking strip 80 so that thereservoir is engaged with the upper surface of wicking strip 80.

In the embodiment of FIG. 9, support cushion 90 is configured similar tosupport cushion 70 of FIG. 8, and includes sidewall 91 of uniform heightthat defines opening 92. Wicking strip 100 is disposed within opening 92so that its upper surface is recessed below the top of sidewall 91 toaccept reservoir 40 and cover 50 as described with respect to precedingembodiments. Preferably, the height of wicking strip 100 is in a rangeof 40-60% of the height of sidewall 91 and is pre-adhered to supportcushion 90 so that the lower surfaces of support cushion 90 and wickingstrip 100 are flush. Wicking strip 100 includes opening 101 that may beused to visually position the unit over a wound, plurality of circularperforations 102 and illustratively, four radially-directed perforations103 that divide the wicking strip into quadrants. Pull tabs 104 areconnected to the innermost ring of the wicking strip in each quadrant.Perforations 102 and 103 extend through the height of the wicking strip,so that the perforations form arcs of predetermined length 105 that maybe individually removed using pull tabs 104.

Support cushion 90 and wicking strip 100 preferably include a layer ofadhesive on the lower surface, similar to layer 25 in the embodiment ofFIG. 1B, which is covered by non-stick liner having removal tab 106.Support cushion 90 also includes a layer of adhesive or other suitablefastening means on its upper surface, and may include a plurality ofslits, as described for preceding embodiments, to improve breathabilityand conformability of the support cushion. Reservoir 40 and cover 50, asdescribed for preceding embodiments, may be employed.

In the embodiment of the invention depicted in FIG. 9, arcs 105 ofwicking strip 100 are configured to be removed, using pull tabs 104, toremove the portion of the wicking strip up to the margin of the wound.Thus, the patient or caregiver would first remove the non-stick linerfrom the support cushion and wicking strip, and align it centered on thewound using opening 101. The patient or caregiver then would remove aselected, and perhaps unequal, number of arcs 105 from each quadrantusing pull tabs to best approximate, or slightly overlap, the margin ofthe wound. The removed arcs 105 of wicking strip 105 then may bediscarded. Once the support cushion and wicking strip are so applied, areservoir and cover, as described for preceding embodiments, is fastenedatop support cushion 90 and wicking strip 100 so that the reservoir isengaged with the upper surface of the wicking strip.

It should be understood that the dressing of FIG. 9 advantageouslypermits an uneven number of selected arcs 105 of the wicking strip to beremoved from each quadrant, thereby enabling the patient or caregiver tobest approximate irregularities in the margin of the wound. This in turnprovides a high degree of protection of the periwound region, withoutthe need to custom fit the entire length of the wicking strip to coverthe periwound region between the support cushion and the margin of thewound, for example, as described with respect to FIG. 4. In addition, itshould be understood that while the wicking strip 100 of the embodimentof FIG. 9 includes four radially-directed perforations, a greater orlesser number of such perforations may be provided, and that sectorsdefined by such perforations need not encompass equal areas.

Referring now to FIG. 10, a further alternative embodiment of a primarydressing 110 is described which provides the ability to periodicallyapply medications or to lavage wound W in epidermis E withoutdisassembling dressing 110. Primary dressing 110 includes supportcushion 111, a wicking strip as described with respect to precedingembodiments (omitted for clarity in FIG. 10), reservoir 112 and cover113. The support cushion, wicking strip, reservoir and cover areconstructed substantially as described for preceding embodiments.Primary dressing 110 differs from preceding embodiments in that supportcushion 111 includes flexible tube 114 that may be permanently orremovably inserted through the sidewall of the support cushion todeliver fluids, such as topical antibiotics or washing fluids throughthe sidewall to wound W, without needing to remove the reservoir andcover. Syringe 115 may be selectively coupled to the distal end of tube114 to inject fluids into primary dressing 110.

In addition, because the primary dressing, when assembled and applied toa patient, provides an essentially closed system (other than bypermitting excess humidity to dissipate through the breathable cover),it is also possible to employ the primary dressing to in negativepressure wound therapy. For example, rather than using syringe 115 inthe embodiment of FIG. 10 to inject fluids into the dressing, by pullingthe piston of an empty syringe, the syringe could be used to create anegative pressure environment in the wound environment. Optionally, thesyringe may include a check valve to assist with maintaining thenegative pressure environment. Alternatively, instead of the syringe115, tube 114 instead may be connected to a conventional squeezeball/valve arrangement or low-pressure vacuum pump to partially evacuatethe dressing. In this manner, the patient or caregiver may periodicallyreduce the pressure within the compartment formed by primary dressing110 to promote exudate flow, and speed the healing process.

With respect to FIG. 11, an alternative design of a primary dressing isdescribed. Dressing 120 includes support cushion 121, a wicking strip asdescribed with respect to preceding embodiments (again omitted forclarity), reservoir 122 and cover 123. The support cushion, wickingstrip, reservoir and cover are constructed substantially as describedfor preceding embodiments. Dressing 120 differs from precedingembodiments in that cover 123 includes bellows 124 that communicateswith the vent that passes through the reservoir (see vent 44 in FIG.1B). Bellows 124 preferably comprises a light-weight plastic orsynthetic rubber and includes one-way valve 125, so that depressingbellows 124 induces a negative pressure within dressing 120. As forpreviously-described embodiments, cover 123 preferably comprises abreathable material that permits excess humidity to be released fromwithin dressing, but is sufficiently air-tight to retain a negativepressure induced within the dressing by bellows 124 for an appropriateamount of time, e.g., 5-10 minutes, to stimulate exudate flow. In thismanner, the patient or caregiver may periodically reduce the pressurewithin the compartment formed by dressing 120 by depressing bellows 124,thereby speeding the healing process with reduced or no pain ordiscomfort to the patient.

Referring now to FIGS. 12A and 12B, a further alternative embodiment ofa primary wound dressing is described. As for the embodiment of FIG. 1,dressing 130 includes three discrete components that are assembled andapplied over wound W on patient's epidermis E. In particular, dressing130 includes support cushion 131, wicking strip 132, and reservoir 133,which may be pre-attached to cover 134. Preferably, components 131-134are sized for use with one another and are enclosed in a sterile packagewith suitable instructions to enable the patient or caregiver to quicklyand accurately apply the dressing.

Support cushion 131 preferably comprises a closed-cell polyolefin foamand is designed to surround wound W and periwound region P, i.e., theregion of epidermis E extending from the wound margin, to protect thewound and elevate reservoir 133 and cover 134 above the wound bed. Inthe embodiment of FIGS. 12A-12B, support cushion 131 has a uniformheight, so that reservoir 133 is supported directly by the upper surfaceof support cushion 131, as depicted in FIG. 12B. As for precedingembodiments, the lower surface of support cushion 131 includes a layer25 of biocompatible adhesive, which preferably is hydrophobic andbreathable, and inhibits contact between exudate and the periwoundregion P. Support cushion 131 preferably includes slits or perforations135 that extend through the height of the support cushion to facilitatethe escape of perspiration from beneath the support cushion when thecushion is fastened to epidermis E. Support cushion 131 includes opening136 that exposes a portion of the periwound region extending away fromthe margin of wound W, to permit placement of wicking strip 132, asdepicted in FIG. 12B. As noted above, support cushion 131 may comprise abreathable open weave spacer fabric instead of a closed-cell polyolefinfoam.

Wicking strip 132, which preferably comprises an open-cell polyurethanefoam, overlays periwound region P between the margin of wound W andopening 136 of support cushion 131. In the embodiment of FIGS. 12A-12B,wicking strip 132 is depicted as a curved strip of foam, although it maytake other forms as described with respect to FIGS. 5A-6B. Wicking strip132 preferably includes a layer 31 of biocompatible adhesive, whichpreferably is hydrophobic and breathable, on its lower surface to adhereto the patient's epidermis and to inhibit contact between exudateabsorbed by the wicking strip and the periwound region P. Duringapplication, wicking strip 132 fits within opening 136 of supportcushion 131, so that the innermost edge of the wicking strip preferablyoverlaps the margin of the wound by 1-2 mm. For the embodiment of FIG.12A, wicking strip 132 may be cut with a scissor to ensure that the foamis not overly compressed when adhered to the periwound region.

Still referring to FIGS. 12A-12B, reservoir 133 preferably comprises asandwich of different density open cell polyurethane foams, as describedwith respect to the embodiment of FIGS. 1A-1C, and comprises one or morefoams selected to absorb exudate from wicking strip 132 and to sequesterthe exudate away from the wound bed. Reservoir 133 may be fastened tothe underside of cover 134, and may include a layer of adhesive alongthe perimeter of its lower surface to adhere to the upper surface ofsupport cushion 131. Reservoir 133 includes a hydrophobic gasket 137disposed on its lateral face, as depicted in FIG. 12B, so that exudatedrawn into the reservoir from wicking strip 132 cannot seep out of thelateral face of the reservoir. Gasket 137 may comprise a hydrophobicfilm applied to the exterior lateral surface of reservoir 133.Alternatively, gasket 137 may comprise a closed cell hydrophobic foamadhered to the perimeter of reservoir 132, which is capable ofsupporting a compressive load (like the material of support cushion131). Reservoir 133 is sized so that its outer edges are supported onthe upper surface of the innermost portions of support cushion 131 andwicking strip 132. Reservoir 133 preferably includes one or more vents138 that assist in modulating the humidity within the dressing throughcover 134.

Cover 134 is preferably a breathable material and overlays reservoir133, and includes a layer of adhesive along the circumference of itslower surface that may be used to removably secure reservoir 133 inengagement with epidermis E and to adhere cover 133 to epidermis E. Inaccordance with one aspect of the present invention, cover 134 includesplurality of holes 139 that permit the reservoir and cover to becorrectly aligned with the wicking strip and support cushion duringapplication. In particular, holes 139 permit the caregiver to sightthrough the holes during application of the cover and reservoir toconfirm proper positioning of the cover and reservoir relative tosupport cushion 131.

As illustrated in FIG. 12B (from which cover 134 has been omitted forclarity), during use of dressing 130, exudate EX flows out of wound W ata flow rate that depends on many factors, including the pressure withwhich wicking strip 132 is pressed against the periwound region, thelateral profile of the wicking strip as described above with referenceto FIGS. 5A-5C, the characteristics of wound W, and the consistency ofthe exudate. As exudate EX is released from the wound, it contacts andis absorbed by wicking strip 132. Wicking strip 132 transports exudateEX laterally (in the plane of epidermis E) and then vertically(perpendicular to the plane of epidermis E) to reservoir 133. Exudatetransported laterally may eventually reach support cushion 131, which isformed of a hydrophobic material, and inhibits further lateral transportof the exudate. Instead, exudate EX is transported vertically fromwicking strip 132 and into reservoir 133, which sequesters exudate awayfrom the wound. Reservoir 133 preferably has a large absorptive surfacearea and the capacity to hold large amounts of exudate, e.g., sufficientcapacity so that reservoir 133 need only be replaced once every fewdays. Additionally, gasket 137 inhibits leakage of exudate ontoperiwound region P. Because reservoir 133 is constructed of a breathablematerial, the water in the exudate absorbed by reservoir 133 is releasedin the form of vapor V into the atmosphere via breathable cover 134.

Referring now to FIGS. 13A and 13B, an alternative embodiment of areservoir and cover suitable for use with a primary dressing isdisclosed. In the embodiment of FIGS. 1A-1C, sidewall 21 providesstructural support for the reservoir against compressive loads appliedto the dressing, while gasket 137 of reservoir 133 provides a similarfunction in the embodiment of FIGS. 12A-12B. As described earlier,however, it may be desirable, with an irregularly shaped wound, tocustom-fit a support cushion using a strip. A problem with thisapproach, however, is that if the reservoir is cut to the overall shapeof the wicking strip and support cushion, the gasket or hydrophobic filmat the edge of the reservoir may be removed, and exudate may leak fromthe exposed edge of the reservoir. One solution is to drape the coverover the sides of the cut reservoir, having this approach does notprovide mechanical support to reservoir to resist compressive loads.

One solution to the foregoing concern is construction for the reservoirand cover depicted in FIGS. 13A and 13B. In this embodiment, cover 140includes rigid inverted basket 141 joined along its lower edge toelastomeric adhesive bandage 142. Reservoir 150, which may be similar inconstruction to reservoir 133 of FIG. 12, and includes gasket 137, isdisposed within basket 141. Basket 141 is formed from plurality ofradial struts 143, circumferential struts 144 and vertical struts 145.Struts 143, 144 and 145 preferably are formed from a tough, resilientplastic, such as polyurethane, and protect reservoir 150 fromcompressive loads.

Advantageously, cover 140 and reservoir 150 are preformed in specificsizes, e.g., small, medium and large diameters. During application ofthe inventive dressing to an irregularly shaped wound, the wicking stripand support cushion may be custom-fit from strip-shaped support cushionand wicking strips by wrapping the support cushion and wicking striparound the wound. A suitably sized cover 140 and reservoir 150 may thenbe selected from the preformed sizes such, when applied, that the outeredge of the reservoir sits atop at least the innermost rings (orspirals) of the support cushion. For example, if the wound is relativelysmall, the reservoir may extend to the outermost ring of the supportcushion. On the other hand, if the wound is large, the reservoir may sitatop the innermost ring of the support cushion. Since for thisembodiment it is not necessary to cut the outer edge of the reservoir,the gasket remains intact and prevents diffusion of exudate through thelateral edges of the reservoir. In addition, the basket providesmechanical support and protection for the reservoir against compressiveloads, thus preventing exudate absorbed into the reservoir from beinginadvertently released into the wound bed.

Primary Dressing Kits

The components of a primary dressing suitable for use with the secondarydressing described herein, illustratively primary dressing 10 of FIGS.1A-1C, may be provided to patients or caregivers as a kit 160,illustrated in FIG. 14. Kit 160 includes a cardboard or other sturdy,disposable backing 161 upon which support cushion 20, wicking strip 30,reservoir 40, and cover 50 are removably mounted. Examples ofalternative disposables backing 161 are dark, colored or translucenttrays of materials such as polystyrenes (for example available fromSealed Air Corp., Elmwood Park, N.J., USA; or Perfecseal®, a BEMIS Co.,Oshkosh, Wis., USA). Kit 160 may also include additional components,e.g., extra wicking strips 30, or different sizes and shapes of supportcushion 20, to be able to accommodate different sizes and shapes ofwounds. In an alternative embodiment, the components of primary dressing10 are instead provided in one or more compartments of a tray.

In the illustrated embodiment, foldable tabs 162 cut from backing 161and/or pieces of excess material adhered to backing 161 may be used tosecure the components of dressing 10 to backing 161 until they areneeded. For example, the hole in support cushion 20 may be formed bycutting piece 163 from a layer of flange material, and then adheringthat piece 163 to backing 161. Because piece 163 snugly fits into thehole of support cushion 20, the friction between piece 163 and supportcushion 20 serves to removably retain support cushion 20 on backing 161without the need for additional adhesive or tabs, until removed by thepatient or caregiver. Similarly, reservoir 40 may be cut from the centerof a larger piece 164 that is subsequently adhered to backing 161.Friction between reservoir 40 and piece 164 retains reservoir 40frictionally engaged on backing 161 without the need for additionaladhesive or tabs, until removed for use. Alternatively, tabs 162 may beused to secure all of the components onto backing 161.

Instructions for use 165 for applying the different components ofdressing 10 to a patient may be printed on backing 161, e.g.,instructions for implementing the method described with respect to FIG.2. The instructions may be sterilized so that they may be safely used ina sterilized field, such as an operating room. The adhesive layers onthe different components are covered with non-stick, removable linersthat may be color coded to guide the patient or caregiver in determiningthe order in which to apply the components of primary dressing 10. Suchnon-stick liners may facilitate handling of the different components ofprimary dressing 10, e.g., while placing support cushion 20 on thepatient's epidermis.

Kit 160 preferably further includes a pouch (not shown) in which backing161 and dressing 10 are sealed until needed. Preferably, the pouch istransparent on at least its upper surface, allowing backing 161 and theother components to be viewed. Additionally, instructions for use 165may be located on backing 161 so as to make possible reading of theinstructions before opening the pouch. The pouch also may be constructedto aid retention of the components of primary dressing 10 on backing161. Kit 160 preferably is sterilizable, e.g., may be sterilized afterassembly, such that the contents of the pouch remain sterile until it isopened, e.g., immediately before the dressing is applied to a patient.The pouch preferably comprises a material that retains its integrityduring conventional sterilizing procedures, e.g., exposure to gammaradiation, to an electron beam, or to ethylene oxide gas.

It is envisioned that a typical wound care treatment environment, suchas a hospital, wound care outpatient clinic or doctor's office, maystock an inventory of kits 160 designed for use with different sizes orshapes of wounds. For example, a plurality of kits 160 may bemanufactured having support cushion 20, wicking strip 30, reservoir 40,and cover 50 in a variety of sizes and shapes, according to differentwound sizes and shapes with which they may be suitable for use.Alternatively, or in addition, individual components of the dressing,such as the wicking strips and reservoirs, may be individually packaged,for example to permit periodic replacement of the wicking strip orreservoir with greater frequency than the dressing as a whole. As astill further alternative, as described above, the wicking strip andsupport cushion may be individually packaged in a roll form or faitfolded configuration, so that the dressing may be applied in acustom-fit manner, while cover and reservoir combinations, such asdescribed above with respect to FIG. 13, may be made available indiscrete sizes, so that the dressing may be applied to a wide range ofwound topologies.

Secondary Dressings

As noted above, the secondary dressings of the present invention may beused to comfortably secure a primary dressing over a wound, thusinhibiting slippage of the primary dressing while at the same timeapplying a desired amount of compression to the primary dressing. Such afeature is particularly useful when the primary dressing is to besecured onto a part of the body where previously-known types ofsecondary dressings cannot readily be placed. For example, the primarydressing may be placed over a sacral ulcer, or over a wound from chestsurgery. It may not be practicable or safe to secure a primary dressingin such a position using a previously-known secondary dressing, such asan ACE™ elastic bandage (3M). For example, using such a bandage tosecure a primary dressing over a sacral, abdominal, hip, ischial, back,breast, buttock, or chest wound typically would require wrapping thebandage around the entire torso, which may undesirably compress internalorgans, may be uncomfortable, and also may be inconvenient to place andremove on a frequent basis. Additionally, depending on the location ofthe primary dressing, the bandage may apply either too little or toomuch pressure to the primary dressing or may shift too readily withmotion, which may fail to properly secure the primary dressing and/ormay worsen the wound. For example, applying too much pressure to adressing applied over a pressure wound may aggravate the wound. Otherbody parts over which it may be difficult to secure dressings includeknee, shoulder (scapula), elbow, and ankle, because of their relativelylarge range of motion during normal use. By comparison, the secondarydressings of the present invention may readily secure a primary dressingover any desired body part, including those enumerated above, and mayapply an appropriate amount of pressure to the primary dressing withoutcompressing other portions of the body. Additionally, the inventivesecondary dressings may allow for stretching if swelling (edema)develops at the wound site.

FIGS. 15A-15B respectively illustrate plan and cross-sectional views ofa secondary dressing 200 constructed in accordance with some embodimentsof the present invention. Dressing 200 includes fabric layer 210, foamsurround 220 (not visible in FIG. 15A) secured to fabric layer 210, andbiocompatible adhesive layer 230 disposed on foam surround 220.Removable liner 240 (not shown in FIG. 15A) optionally protectsbiocompatible adhesive layer 230 until secondary dressing 200 is readyfor use, at which point the liner may be removed to expose adhesivelayer 230 for securement to the patient's epidermis. As can best be seenin FIG. 15B, fabric layer 210 is secured to foam surround 220 viaadhesive layer 223, which may be substantially the same as biocompatibleadhesive layer 230. However, any suitable means for securing fabriclayer to foam surround 220 may be used. In one example, adhesive layer223 is a thin (e.g., 1/32″) layer of foam adhesive.

FIG. 15C schematically illustrates a cross-section of secondary dressing200 applied over primary dressing 10 described above with reference toFIGS. 1A-1C. Biocompatible adhesive 230 is secured to the patient'sepidermis E, while fabric layer 210 is disposed over cover 50 of primarydressing 10. Fabric layer 210 can be seen to conform to dressing 10, andto provide a smoothly varying profile between the outer edges ofdressing 10 and epidermis E, enabling bed sheets, clothing, or otherdressings to slide relatively easily over secondary dressing 200.Additionally, the height differential between cover 50 and foam surround220 imposes tension T on fabric layer 210, gently compressing dressing10 against epidermis E. In some embodiments, the magnitude of tension Tmay be adjusted by selecting the elasticity of fabric layer 210 in oneor both lateral dimensions, as described in greater detail below. Ingeneral, the greater the elasticity of fabric layer 210, the lower thetension T that secondary dressing 200 will apply to the primarydressing. Tension T, coupled with the smooth profile provided by fabriclayer 210, help to secure primary dressing 10 to the epidermis andreduce the risk that dressing 10 will slip from its initial positionbecause of interactions with bed sheets, clothing, other dressings, orthe like.

As FIG. 15C illustrates, fabric layer 210 has larger dimensions than theprimary dressing with which it is to be used, e.g., primary dressing 10described above with reference to FIGS. 1A-1C. Foam surround 220 extendsto the periphery 213 of fabric layer 210, and also has defined therein acentral aperture 250 (best seen in FIGS. 15A-15B) with larger dimensionsthan the primary dressing. Alternatively, as described below withreference to FIG. 20, the periphery 213 of fabric layer 210 may extendbeyond foam surround 220, e.g., by at least half an inch in eachdirection. In general, the respective sizes and shapes of fabric layer210 and aperture 250 may be appropriately selected for use with primarydressings of any desired size or shape. For example, fabric layer 210may have a width between 2 inches and 20 inches in one or both lateraldimensions, e.g., between 4 and 18 inches, or between 6 and 16 inches,or between 8 and 14 inches. Aperture 250 may, for example, have a widthbetween 1 inch and 18 inches in one or both lateral dimensions, orbetween 2 and 16 inches, or between 4 and 14 inches, or between 6 and 12inches. Additionally, fabric layer 210 and aperture 250 are preferablysized relative to each other such that the portion of foam surround 220and adhesive 230 disposed thereon has sufficient surface are toadequately secure the primary dressing in place. In various embodiments,one or both of fabric layer 210 and central aperture may be square,rectangular, triangular, polygonal, round, oval, curved, or irregularlyshaped, optionally with rounded corners, e.g., as illustrated in FIG.15A. In one preferred embodiment, fabric layer 210 is approximately 8inches square, and aperture 250 has a diameter of 6 inches.

FIG. 16 illustrates steps in an exemplary method 1600 of using asecondary dressing, e.g., secondary dressing 200 illustrated in FIGS.15A-15C, with a primary dressing. First, at step 1610, a caregiverobtains and applies a primary dressing over a wound. For example, inembodiments where the primary dressing is dressing 10 described abovewith reference to FIGS. 1A-1C, the caregiver may implement the steps ofmethod 60 illustrated in FIG. 2. However, it should be understood thatthe secondary dressing 200 can be used with any suitable primarydressing. Examples of suitable primary dressings with which secondarydressing 200 may be used include primary dressings for chronic woundsand primary dressings for acute (e.g., incisional) wounds. For example,secondary dressing 200 may suitably be applied over a hydrocolloiddressing, a foam dressing, an ABD (abdominal) pad dressing, sutures,staples, an adhesive (e.g., steri strips), a gauze pad, a nonwoven pad,a surgipad and/or a skin glue. In one specific embodiment, the primarydressing is a dressing described in copending U.S. patent applicationSer. No. 12/504,590, filed Jul. 16, 2009 and entitled “Systems andMethods for Protecting Incisions,” the entire contents of which areincorporated by reference herein.

Then, at step 1620, the caregiver obtains secondary dressing 200, andconfirms that secondary dressing 200 is appropriately sized for use withthe primary dressing, for example by approximately positioning dressing200 over the primary dressing and confirming that all dimensions ofaperture 250 are larger than the primary dressing. Then, at step 1630,the caregiver applies secondary dressing 200. For example, the caregivermay remove removable liner 240 from biocompatible adhesive 230 and applythe adhesive to the patient's epidermis such that aperture 250 isapproximately centered on the primary dressing. This step secures foamsurround 220 about the primary dressing, disposes fabric layer 210 overthe top surface of the primary dressing, and applies tension on fabriclayer 210 that secures the primary dressing against the patient'sepidermis. Optionally, the caregiver may adjust the tension that thesecondary dressing applies to the primary dressing (step 1640). Forexample, the caregiver may select the orientation of the fabric of thesecondary dressing and/or may apply tension to the patient's epidermiswhile applying the secondary dressing, so as to further adjust thetension on fabric layer.

It should be noted that in some circumstances, the primary dressing mayinclude features that remain outside of secondary dressing 200. Forexample, as described above with reference to FIG. 10, the primarydressing may include tubing connected to a syringe or other reservoirthat may be used to introduce material to the wound and periwound regionand/or to remove material from the wound and periwound region. Suchtubing, for example, may be passed under foam surround 220, enabling acaregiver to access the reservoir and thus introduce and/or removematerial from the wound and periwound region via the tubing without theneed to remove the secondary or primary dressings.

The secondary dressing can alternatively be applied directly over aregion of compromised skin, e.g., over a wound, diseased skin (such asskin affected by shingles), or otherwise unhealthy skin, without the useof a primary dressing. In such embodiments, secondary dressing 200 ispreferably sized and configured such that aperture 250 is larger thanthe affected region of skin, so as to avoid contact between adhesive 230and the affected region of skin. Moreover, the inventive secondarydressing can be applied over more than one other dressing, e.g., can beapplied over other secondary dressings, or even over tertiary dressings,to secure such dressings in place.

Further details of the components of secondary dressing 200, and somealternative embodiments, will now be described.

Referring again to FIGS. 15A-15C, fabric layer 210 preferably isbreathable, with an MVTR that is at least as great as an MVTR of theprimary dressing with which it is to be used. As such, when applied overthe primary dressing, fabric layer 210 does not significantly slow theevaporation of vapor out of the primary dressing. Such a feature may beparticularly useful in embodiments where secondary dressing 200 is usedin combination with primary dressing 10 described above. As noted above,primary dressing 10 is designed to facilitate the transfer of a fluidaway from a wound bed and periwound region and into a reservoir. Thefluid may evaporate from the reservoir and through secondary dressing200, inhibiting maceration while keeping the wound sufficiently moist.Fabric layer 210 may include any suitable breathable fabric, such as awoven fabric or non-woven fabric, which may be synthetic, natural, or amixture of synthetic and natural fibers. For example, in one embodiment,fabric layer 210 is an open weave polyester mesh. Optionally, fabriclayer 210 is impregnated with a therapeutic composition, such as anysuitable antibacterial or antimicrobial agents (e.g., silver), thatinhibits bacterial growth or performs another suitable therapeuticfunction.

In some embodiments, fabric layer 210 may have different elasticities ineach of its two lateral dimensions, which may enable the caregiver tobetter adjust the tension T that fabric layer 210 applies to the primarydressing. For example, as illustrated in FIG. 17, fabric layer 210′ mayhave a greater amount of stretch or elasticity in the machine (M)direction as compared to the cross (C) direction. The M and C directionsof fabric layer 210′ may be suitably oriented relative to foam surround220 during the manufacturing process. Removable liner may have aplurality of asymmetrically configured tabs designed to facilitate thecaregiver's recognition of the more elastic direction of the fabric,and/or fabric layer 210′ may include markers indicating the more elasticdirection of the fabric. Either or both of these features may assist thecaregiver in determining how to orient secondary dressing 200 relativeto the primary dressing. For example, if the caregiver applies thedressing of FIG. 17 beginning from left to right (parallel to themachine direction), then fabric layer 210′ will stretch by a relativelylarge amount as it is brought to overlay the primary dressing, resultingin less compression of the primary dressing. By contrast, if thecaregiver instead applies the dressing from top to bottom (perpendicularto the machine direction), then fabric layer 210′ will stretch by arelatively small amount as it is brought to overlay the primarydressing, resulting in more compression of the primary dressing. Thecaregiver may orient the M and C directions of the fabric at any desiredangle relative to the primary dressing, so as to select a particularmagnitude of tension on the fabric that is appropriate to the primarydressing and the wound.

Referring back to FIGS. 15A-15B, foam surround 220 may include arelatively thin layer (e.g., less 0.25″) of any suitable foam, forexample, a closed-cell polyolefin foam. As for the support cushiondescribed further above with respect to FIGS. 1A-1C, foam surround 220optionally may have a plurality of slits or apertures defined therein toenhance the breathability of foam surround 220. Foam surround 220 may insome embodiments be replaced by a polyurethane layer. Alternatively, asillustrated in FIG. 18, a single adhesive layer 270 may be used in placeof adhesive layer 223, foam surround 220, and biocompatible adhesivelayer 230. Adhesive layer 270 may be a relatively thick layer ofadhesive that has substantially the same lateral profile as foamsurround 220. Optionally, adhesive layer 270 may be reinforced with awoven fabric or a nonwoven fabric. Adhesive layer 270 may be providedalready applied to fabric layer 210, and have removable liner 271disposed thereon to protect layer 270 until ready for use. In analternative embodiment (not illustrated), adhesive layer 270 may beprovided separately from fabric layer 210, and have removable linersdisposed on both of the major surfaces of layer 270. During use, a firstremovable liner may be removed to expose a first major surface of layer270, which surface may then be applied to the patient's epidermis. Thesecond removable liner may then be removed to expose the other majorsurface of layer 270, to which fabric layer 210 may then be applied.

As noted above with reference to FIGS. 15A-15C, fabric layer 210provides a relatively smooth profile over which other fabrics mayreadily glide, reducing the probability that those other fabrics maycause the primary dressing to slip from its desired position on theepidermis. As illustrated in FIG. 19, the profile of secondary dressing200′ may further be smoothed by tapering the height profile of foamsurround 220′, as well as adhesive layers 223′, 230′.

In another illustrative embodiment, as illustrated in FIGS. 20A-20B,dressing 200″ includes alternative fabric layer 210″ having an extendedperiphery 213″ configured to extend beyond the perimeter of foamsurround 220″, e.g., by half an inch in each direction. Such a featureis useful because it inhibits the edge of secondary dressing fromlifting, and provides a smooth, comfortable surface over which clothingand bed linens may slide freely. Additionally, the extended periphery offabric layer 210″ may inhibit any residual adhesive at the edge of foamsurround 220″ from contacting clothing or bed linens. Alternativedressing 200″ also includes modified foam surround 220″ having aplurality of perforations 280 defined therein, e.g., four perforations280 on the diagonals of foam surround 220″ and configured to separatefoam surround 220″ into four portions of approximately equal size.Perforations 280 provide dressing 200″ with enhanced control over thetension applied to fabric layer 210″. Specifically, perforations 280allow each portion of foam surround 220″ to be pulled independently, soas to adjust the tension on fabric layer 210″. Additionally,perforations 280 provide enhanced versatility in the size of secondarydressing 200″ and its use over primary dressings of different sizes, aswell as enhanced positioning on different parts of the body, becauseeach portion of foam surround 220″ may be separated from the others andmoved independently to an appropriate location. It should be understoodthat not all embodiments of dressing 200″ need include both perforations280 and an extended fabric periphery 213″; for example, a dressing mayhave only perforations 280 and no extended periphery 213″, or may haveonly extended periphery 213″ but no perforations 280.

While various illustrative embodiments of the invention are describedabove, it will be apparent to one skilled in the art that variouschanges and modifications may be made therein without departing from theinvention. The appended claims are intended to cover all such changesand modifications that fall within the true spirit and scope of theinvention.

What is claimed:
 1. An apparatus for protecting a region of compromisedskin, the apparatus comprising: a primary dressing configured forapplication over the region of compromised skin, the primary dressingcomprising fluid-absorbing material; and a secondary dressing configuredfor application over the primary dressing, the secondary dressingconfigured to apply pressure to the primary dressing so as to maintainthe primary dressing in place over the region of compromised skin and soas to promote the flow of fluid from the region of compromised skin intothe fluid-absorbing material, the secondary dressing further configuredto allow moisture in the fluid to evaporate from the fluid-absorbingmaterial, wherein the secondary dressing comprises a fabric layer and abiocompatible adhesive layer, the adhesive layer disposed along aperiphery of the fabric layer and configured to secure the fabric layerover the primary dressing, wherein the secondary dressing furthercomprises a foam layer disposed between the fabric layer and thebiocompatible adhesive layer, the foam layer having an aperture therein,the aperture being larger than the primary dressing.
 2. The apparatus ofclaim 1, wherein the fabric layer comprises a woven fabric or a nonwovenfabric.
 3. The apparatus of claim 1, wherein the fabric layer has amachine direction and a cross direction, and wherein an elasticity ofthe fabric layer is different in the machine direction than anelasticity of the fabric layer in the cross direction.
 4. The apparatusof claim 3, wherein the pressure applied by the secondary dressing onthe primary dressing is based on an orientation of the machine and crossdirections of the fabric layer.
 5. The apparatus of claim 1, wherein theprimary dressing comprises a strip of the exudate-absorbing material,the strip having first and second ends, a lower surface, an uppersurface, and a length, the upper and lower surfaces being parallel toone another along the length.
 6. The apparatus of claim 5, wherein thestrip is adapted to flex along its length to circumscribe the region ofcompromised skin.
 7. The apparatus of claim 5, wherein the primarydressing further comprises an adhesive disposed on the lower surface ofthe strip, the adhesive securing the strip adjacent the region ofcompromised skin.
 8. The apparatus of claim 1, wherein the primarydressing further comprises a support cushion configured to surround theregion of compromised skin and the exudate-absorbing material.
 9. Thedressing of claim 8, wherein the primary dressing further comprises abiocompatible adhesive configured to secure the support cushion aroundregion of compromised skin and the exudate-absorbing material.
 10. Theapparatus of claim 1, wherein the secondary dressing has a moisturevapor transfer rate (MVTR) that is greater than an MVTR of the primarydressing.
 11. An apparatus for protecting a region of compromised skin,the apparatus comprising: a primary dressing configured for applicationover the region of compromised skin, the primary dressing comprisingfluid-absorbing material; and a secondary dressing configured forapplication over the primary dressing, the secondary dressing configuredto apply pressure to the primary dressing so as to maintain the primarydressing in place over the region of compromised skin and so as topromote the flow of fluid from the region of compromised skin into thefluid-absorbing material, the secondary dressing further configured toallow moisture in the fluid to evaporate from the fluid-absorbingmaterial, wherein the primary dressing further comprises a reservoirconfigured to be suspended over and in engagement with theexudate-absorbing material so that the material transfers exudate fromthe region of compromised skin to the reservoir.
 12. The apparatus ofclaim 11, wherein the primary dressing further comprises a coverconfigured to be positioned over the reservoir, the secondary dressingbeing in contact with the cover.